Classes of Data

There are 3 types of Data:
Master Data
Transaction Data
Configuration Data
Master Data:
It represents the business entities in an ERP System like SAP R/3
Many times it is organizational entities such as the company, plan, sales area, cost centre, or an Account. Other times it represent external entities such as customers and Vendors. It may represent things such as Materials.
Master Data Itself can take on various forms. SAP BW Caterogizes Master Data into 3 forms.
1.Attributes
2.Text
3.Hierarchies.
Attributes are any fields that describe a MD Entity. Attributes are classified into 1.Display Attributes
2. Navigational Attributes
Text table simply contains the textual descriptions of MD and are usually stored in separate tables because they are language dependent.
Hierarchies are most separate tables that store parent and child relationships between MD entities such as a cost center hierarchy or a product hierarchy.
There are 4 types of hierarchy tables.
Hierarchy tables (H)
Hierarchy SID table(K)
SID Hierarchy Structure table(I)
Hierarchy Interval Table(J)

Transaction Data:
It describes a business event such as a sales order or the result of Business Processes. Example:Current
In stock quantity of a specific product, sales revenue etc.. Transaction Data contains the preponderant(Major)
share of the key figures that will become your fact table in sap bw info cubes.
There are 2 conceptual levels of a Transaction Data.
1.Document Level
2.Summary Level
Document Level: The Document Level may consists of several tables. Most commonly, there are upto 3 level of details for the document level.
They are 1. Headers
2.Line Items
3.Schedule Lines
Header Information normally contains information about the document itself. It includes Document type, Document Creation Date, Document created by, Document number etc.,
The Line items consists of details of the document such as materials on a purchase order or general ledger accounts on a financial transaction.
Schedule Line details usually revolve around the delivery schedules where a given quantity of a specific product ordered has to be broken into several scheduled deliveries because it provides the largest amount of information, usually the lowest level of granularity is the ideal source of exraction.

Summary Level: Dynamic summary tables are redundant summarizations of line items data and primarily exist in the ERP Systems for reporting purpose.
My SAP's Special Ledger(FI/SL) and logistics information system(LIS) are the common examples.
My ERP HR, the distinction between master and Transaction is blurred. HR Infotypes - a hybrid between Master and Transaction datasources details such as personal data and payroll results as infotype data.

Configuration Data: It drives the ERP Application logic. Typically many configuration tables can be found in a ERP System. The realty of a highly customizable enterprise wide software solutions was achieved through data drives application logic.